Inflator

ABSTRACT

An inflator is located inside an airbag of airbag device for supplying inflation gas. The inflator includes a substantially cylindrical body for generating inflation gas, and a substantially tubular retainer made of sheet metal to be mounted around the body for holding the body by fastening a fastening portion. The retainer includes mounting bolts for mounting the airbag to a predetermined mounting position. The retainer includes a fastening portion, a first support portion and a second support portion which are arranged in order along axial direction of the body to abut against a circumference of the body. The fastening portion and the second support portion are located in a substantially opposite area from the first support portion in the circumference of the body based on a center of a cross section of the body taken perpendicularly to the axial direction of the body as the retainer holds the body.

The present application claims priority from Japanese Patent ApplicationNo. 2003-392316 of Mabuchi, filed on Nov. 21, 2003, and Japanese PatentApplication No. 2004-218667 of Mabuchi et al., filed on Jul. 27, 2004,the disclosures of which are hereby incorporated into the presentapplication by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an inflator for supplying inflation gasto an airbag of airbag device for automobile which is used in aninserted state in the airbag.

2. Description of Related Art

Japanese Patent Laid-Open No. 2001-171468 discloses an inflator for aside impact airbag device mountable on a vehicle seat. The inflator isinserted within an airbag for supplying the airbag with inflation gas.The inflator includes a substantially cylindrical body for generatinginflation gas, and a substantially tubular retainer made of sheet metaland mounted around the body for holding the body. The retainer includesa mounting means for mounting the airbag to a predetermined mountingposition.

U.S. Pat. No. 5,687,988 discloses an inflator which is provided in anend face of a cylindrical body thereof with a flat mounting stud. Aretainer made of sheet metal for holding the body is formed into ahalf-pipe shape which is open upward for supplying inflation gas. One oftwo axial ends of the retainer is provided with an end wall, and thisend wall includes a slot for receiving the mounting stud. Adjacent to anopen end opposing to the end wall having the slot is an arm which isplastically deformed to clamp the inflator body like a belt. When theinflator body is held by the retainer, the mounting stud of the body isinserted into the slot of the retainer, and the arm is deformed tobelt-fasten the body. Thus both ends of the body is held by the retainerby the mounting stud fitted in the slot and the arm abutting against acircumference of the body, so that the inflator body is prevented fromlifting out toward the gas supplying opening. The arm contacting thecircumference of the inflator body prevents the body from sliding outfrom the open end side of the retainer.

In the inflator in the former reference, the inflator body is held bythe retainer by fastening two fastening portions both of which arelocated in the vicinity of an axial center of the retainer. The inflatoris put in the airbag in that state, and the airbag is folded to assemblean airbag device. When the airbag is folded, accordingly, the work hasto be done in an environment considering malfunction of the inflatorinserted in the airbag, which complicates the folding work of theairbag.

It might be possible to insert the inflator in the airbag after thefolding work of the airbag. However, the mounting means such as boltsfor mounting the airbag to the mounting position are protruded from theretainer of the inflator, and the mounting means obstruct insertion ofthe inflator in the airbag after the folding work of the airbag.

It also might be possible to insert the retainer only in the airbagfirstly, and then set the inflator body in the retainer after thefolding work of the airbag. However, the fastening portions of theconventional retainer are located in axial center. In the foregoingprocesses, the fastening portions arranged inside the folded airbag haveto be fastened from outside of the airbag, which may damage the airbag.

As to the inflator in the latter reference, it might be possible toinsert the retainer only in the airbag such that the arm of the retaineris located out of the airbag, and then to fold the airbag and set theinflator body in the retainer by inserting the mounting stud in the slotof the retainer. Then the arm is fastened for the retainer to hold thebody. With this arrangement, however, it is difficult to insert themounting stud into the slot located inside the airbag, since the slot isnot visible. Therefore, the assembling work of the inflator is not easy,either.

SUMMARY OF THE INVENTION

The present invention contemplates to solve the abovementioned problems,and therefore, has an object to provide an inflator which is assembledeasily even if a retainer is located inside a folded airbag, and thusfacilitates a folding work of the airbag.

The inflator according to the present invention is disposed inside anairbag for airbag device for supplying inflation gas. The inflatorincludes a substantially cylindrical body for generating inflation gas,and a substantially tubular retainer made of sheet metal for beingmounted around the body. The retainer includes a mounting member formounting the airbag to a predetermined mounting position, a fasteningportion, a first support portion and a second support portion. Thefastening portion is fastened on the body set in the retainer by beingplastically deformed and recessed inward such that the retainer holdsthe body. While the fastening portion is located in the vicinity of oneend of the retainer, the fastening portion, the first support portionand the second support portion are arranged in order along axialdirection of the body to abut against a circumference of the body, suchthat the retainer holds the body at least at three axial positions bythe fastening portion, the first support portion and the second supportportion. Furthermore, the fastening portion and the second supportportion are located in a substantially opposite area from the firstsupport portion in the circumference of the body based on a center of across section of the body taken perpendicularly to the axial directionof the body as the retainer holds the body.

In the inflator of the present invention, the fastening portion islocated at an end of the retainer. This allows the retainer to beinserted into the airbag while the fastening portion is exposed out ofthe airbag, and further enables the airbag to be folded up in thatstate. Moreover, since the fastening portion is exposed out of theairbag after the airbag is folded up, the inflator body can be insertedinto the retainer, and the fastening portion exposed out of the airbagcan be fastened directly, not from outside of the airbag. Accordingly,the inflator body is easily joined with the retainer having been put inthe folded airbag without damaging the airbag. In addition, the body iseasily set in the retainer merely by inserting the body into theretainer.

Moreover, the retainer arranges the fastening portion, the first supportportion and the second support portion along the axial direction of theinflator body to abut against the circumference of the inflator body. Inthe circumference of the inflator body based on a center of a crosssection of the body taken perpendicularly to the axial direction of thebody as the retainer holds the body, the fastening portion and thesecond support portion are located in a substantially opposite area fromthe first support portion. Accordingly, when the fastening portion isfastened after the retainer is set in the body, the inflator bodyfunctions as a lever. More particularly, the fastening portion serves aseffort-point, the first support portion serves as a fulcrum, and thesecond support portion serves as an application-point, such that thesecond support portion is pressed onto the body. In other words, theinflator body is stably supported at least at three positions in theaxial direction by the fastening portion, and the first and secondsupport portions.

Of course, although the retainer includes amounting means, the retaineris located inside the airbag smoothly since it is inserted into theairbag before being folded up.

Therefore, in the inflator of the present invention, the inflator bodyis easily joined with the retainer even if the retainer has already beenput in the folded airbag. Moreover, the folding work of the airbag isfacilitated since the airbag is folded up in a state only the retaineris inside the airbag before the inflator body is inserted into theairbag.

In the above inflator, it is desired that the fastening portion isprojected from the airbag when the inflator is inserted and located inthe airbag. At this time, it is sufficient that the fastening portion isexposed outside of the airbag upon fastening the fastening portion.Accordingly, for example, it will be appreciated that an airbag isfolded in a state an entire retainer except the mounting means isdisposed inside the airbag, the inflator body is inserted into theretainer from a predetermined insert hole of the airbag, and that thefastening portion located at the end of the inflator disposed proximateto the insert hole is exposed by turning back an edge of the insert holeof the airbag, and then fastening work is applied. Thereafter, the edgeportion of the insert hole is restored.

However, if the inflator is configured so that the fastening portion ofthe retainer is projected from the airbag in the folding step of theairbag, too, the assembling work of the airbag device is even morefacilitated since there is no need to turn over and restore the edge ofthe insert hole of the airbag.

If gas discharge ports of the body are located at an end of the bodyapart from the fastening portion such that inflation gas is fed to theairbag from a location apart from the fastening portion, inflation gasis prevented from unexpectedly flowing out in the course of inflationafter the inflator body is inserted into the retainer having beenalready disposed in the airbag from the insert hole of the airbag, evenif the insert hole is not closed.

If the retainer includes a positioning projection for positioning theinflator body in the retainer by abutting against the body when the bodyis inserted into the retainer from a side of the fastening portionbefore fastened, moreover, the inflator body is easily positioned in theretainer which is disposed invisibly in the airbag when abutting againstthe positioning projection, which facilitates the assembling work of theairbag device.

It is desired that the second support portion is located in the vicinityof an end of the retainer apart from the other end having the fasteningportion. With this construction, the inflator body is held in thelongest span by the fastening portion and the second support portioneach of which is located in the vicinity of end of the retainer.Therefore, the retainer holds the body stably.

Moreover, it is desired that the first support portion is locatedsubstantially in an axial middle position in the retainer. With thisconstruction, the first support portion is proximate a middle positionbetween the fastening portion and the second support portion, andtherefore, the retainer holds the body well-balancedly.

Moreover, it is desired that the first support portion and the secondsupport portion are beads that are made by pressing a sheet metalforming the retainer. With this construction, the first and secondsupport portions are easily made by pressing work.

It will also be appreciated that at least one of the fastening portion,the first support portion, or the second support portion includes twocontact points that project inward to contact the circumference of theinflator body and are arranged along a circumferential direction of theretainer. With this construction, two contact points hold the body, sothat the body is prevented from being dislocated in a directionperpendicular to the axial direction, and is held by the retainerstably.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a side impact airbag device employing an inflatoraccording to the present invention in service;

FIG. 2 is a schematic cross section of the side impact airbag device ofFIG. 1, taken along line II-II of FIG. 1;

FIG. 3 is a front view of an embodiment of the inflator of the presentinvention;

FIG. 4 is a bottom view of the inflator of FIG. 3;

FIG. 5 is a schematic vertical section of the inflator of FIG. 3, takenalong line V-V of FIG. 4;

FIG. 6 is a perspective view of a retainer of the inflator of FIG. 3;

FIGS. 7A to 7D illustrate assembling processes of the inflator of FIG. 3to an airbag in order;

FIG. 8 is a sectional view of the airbag of FIG. 7, taken along lineVIII-VIII of FIG. 7A;

FIGS. 9A and 9B illustrate a fastening state of a fastening portion ofthe retainer in the inflator of FIG. 3, which correspond to line IX-IXof FIG. 3;

FIG. 10 is a schematic vertical section of another embodiment of theinflator;

FIG. 11 is a perspective view of a retainer of the inflator of FIG. 10;

FIG. 12 is a schematic cross section of the inflator of FIG. 10, takenalong line XII-XII of FIG. 11;

FIG. 13 is a schematic cross section of the inflator of FIG. 10, takenalong line XIII-XIII of FIG. 11;

FIG. 14 is a schematic vertical section of yet another embodiment of theinflator;

FIG. 15 is a perspective view of a retainer of the inflator of FIG. 14;

FIG. 16 is a schematic cross section of the inflator of FIG. 14, takenalong line XVI-XVI of FIG. 15;

FIG. 17 is a schematic cross section of the inflator of FIG. 14, takenalong line XVII-XVII of FIG. 15;

FIG. 18 is a schematic vertical section of still another embodiment ofthe inflator;

FIG. 19 is a perspective view of a retainer of the inflator of FIG. 18;

FIG. 20 is a schematic cross section of the inflator of FIG. 18, takenalong line XX-XX of FIG. 19;

FIG. 21 is a schematic cross section of the inflator of FIG. 18, takenalong line XXI-XXI of FIG. 19; and

FIG. 22 is a perspective view of a retainer employed in still anotherembodiment of the inflator.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention are described below withreference to the accompanying drawings. However, the invention is notlimited to the embodiments disclosed herein. All modifications withinthe appended claims and equivalents relative thereto are intended to beencompassed in the scope of the claims.

FIGS. 1 and 2 illustrate an embodiment of the inflator 20 of the presentinvention. The inflator 20 is part of a side impact airbag device Mlocated in an exterior side 2 a of a seat back portion 2 of a seat 1.

The seat back portion 2 includes a seat frame 3 which is arrangedgenerally vertically, and the side impact airbag device M is secured tothe seat frame 3 by a later-described retainer 25 by bolts 37 and nuts7. In FIG. 2, a member with reference numeral 4 is a cushion, andmembers with reference numerals 5 and 6 are surface skins made ofdecoration fabric or the like. A left edge portion 4 a of the cushion 4covers the side impact airbag device M from front part to vehicle'sexterior part. Upon deployment of an airbag 15, the edge portion 4 a ispushed by the airbag 15 and separated from a center part 4 b of thecushion 4.

The side impact airbag M includes an airbag 15, and an inflator 20arranged inside the airbag 15 for supplying the airbag 15 with inflationgas.

As shown in FIGS. 1, 7 and 8, the airbag 15 is made into a bag shapeincluding an interior wall 15 a and an exterior wall 15 b, and isadapted to protect breast of an occupant D (FIG. 1 shows a dummy) seatedin the seat 1 upon deployment. Upon deployment of the airbag 15, theinflator 20 is located at a rear end of the airbag 15. In a rear endpart of the interior wall 15 a of the airbag 15 are two through holes 16for allowing bolts 37 of the retainer 25 of the inflator 20 to protrudetherefrom. The airbag 15 is made of a single piece of fabric ofpolyester, polyamide or the like. This fabric is folded in two forwardat a position corresponding to a rear end of the completely inflatedairbag 15, and then is stitched up at overlaid outer edges by stitchingyarn 13, and thus the airbag 15 is formed.

When the outer edges of the fabric are stitched up, a portioncorresponding to a rear lower end of the completely deployed airbag 15is left unstitched. This unstitched portion serves as an insert hole 15c for inserting the retainer 25 of the inflator 20 into the airbag 15therefrom.

Although seam allowances in the outer edge of the airbag 15 are exposedon surface in the illustrated embodiment, the airbag 15 may be soconfigured as not to expose the seam allowances outside, by turning overthe airbag 15 utilizing the insert hole 15 c, for example.

Moreover, although the insert hole 15 c of the airbag 15 is formed in alower part proximate the rear end, the insert hole 15 c may be formed inan upper part proximate the rear end of the airbag 15. In that case, alater-described fastening portion 35 of the inflator 20 is arranged toprotrude upward from the upper portion proximate the rear end of theairbag 15, contrarily to the illustrated embodiment.

As shown in FIGS. 2 to 6, the inflator 20 includes a substantiallycylindrical body 21 for generating inflation gas, and a substantiallytubular retainer 25 made of sheet metal. The retainer 25 is mountedaround the inflator body 21 to hold the body 21, and includes bolts 37as mounting means for mounting the airbag 15 on a predetermined positionof the seat back 2.

The inflator body 21 includes a substantially cylindrical greaterdiameter portion 22 and a small diameter portion 23 projected from oneend face (or an end face oriented upward when the inflator 20 is mountedon the seat back 2) of the greater diameter portion 22. The smalldiameter portion 23 includes a plurality of gas discharge ports 23 a fordischarging inflation gas when actuated. In the other end portion of thegreater diameter portion 22 is a connector portion 22 a for joining aharness 39 thereto for connection with an airbag actuating circuit. Inthe vicinity of the connector portion 22 a of the greater diameterportion 22 is a recessed portion 22 b on which a fastening portion 35 ofthe retainer 25 is fastened. The harness 39 includes a connector 39 alocated at an end of its lead wire 39 b to be connected to the connectorportion 22 a.

The retainer 25 includes a tubular portion 26 made of sheet metal andtwo bolts 37 secured to the tubular portion 26 as mounting means. Thebolts 37 line up along axial direction of the tubular portion 26, andproject inward of the vehicle when the retainer 25 is mounted on theseat back 2.

The tubular portion 26 has openings 26 a and 26 b in its axial ends, andincludes three apertures 27, 29 and 34 in its circumference, indescending order as mounted on the seat back 2 as shown in FIGS. 3, 5and 6. The uppermost aperture 27 serves as a gas outlet port 27 forletting out inflation gas from the gas discharge ports 23 a, and themiddle aperture 29 serves as a lightening hole 29 for weight reduction.The lowermost aperture 34 serves as a slit 34 for providing thefastening portion 35. These apertures 27, 29 and 34 are mainly openedforward and toward exterior of the vehicle as the inflator 20 is mountedon the seat back 2. The airbag 15 mounted on the seat 1 is configured todeploy forward at exterior side of the seat 1, as indicated bydouble-dotted lines in FIG. 2, by inflation gas flown out of the gasoutlet port 27 of the retainer 25.

Inflation gas discharged from the gas discharge ports 23 a of theinflator body 21 are supplied into the airbag 15 from an upper endopening of the tubular portion 26 serving as a gas outlet port 26 a, aswell as from the gas outlet port 27. The retainer 25 includes a coverportion 28 between the outlet ports 27 and 26 a for covering the gasdischarge ports 23 a when the body 21 is held by the retainer 25, suchthat inflation gas is supplied into the airbag 15 dispersedly from thegas outlet port 27 and the gas outlet port 26 a.

In a periphery of the gas outlet port 27 is a positioning projection 26c to abut against an end face of the greater diameter portion 22 of theinflator body 21 such that the vicinity of the gas discharge ports 23 astops at a position of the cover portion 28 when the body 21 is insertedfrom the opening 26 b of the retainer 25.

The fastening portion 35 of the retainer 25 is located at an end of theretainer 25 which becomes a lower end as mounted on the seat back 2. Thefastening portion 35 includes a knob portion 35 a having an invertedU-shaped section, and two clamping portions 35 b and 35 c. The clampingportions 35 b and 35 c are located in both sides of the knob portion 35a in a circumference of the tubular portion 26, and are bent inward ofthe tubular portion 26. The fastening portion 35 is operated by holdingthe knob portion 35 a circumferentially of the tubular portion 26 andplastically deforming the knob portion 35 a, such that the clampingportions 35 b and 35 c are projected inward of the tubular portion 26and pressed on a bottom face 22 c of the recessed portion 22 b of theinflator body 21.

The clamping portions 35 b and 35 c are located in a vehicle's frontpart of the outer circumference of the greater diameter portion 22 ofthe inflator body 21 as mounted on the seat back 2, based on a center Cof a section of the body 21 taken perpendicularly to the axis of thebody 21 as shown in FIG. 4, when pressed onto the recessed portionbottom face 22 c of the body 21.

The tubular portion 26 of the retainer 25 is configured to hold andclamp the inflator body 21 at least at three positions along the axialdirection of the body 21 including the clamping portions 35 b and 35 cof the fastening portion 35. More specifically, the fastening portion35, a first support portion 31, and a second support portion 32 arearranged in ascending order to abut against the circumference of theinflator body 21 along the axial direction.

The second support portion 32 is located proximate to an end of thetubular portion 26 apart from the fastening portion 35, in a bandportion 30 disposed between the gas outlet port 27 and the lighteninghole 29. The first support portion 31 is located generally in a middleposition between the fastening portion 35 and the second support portion32. In the illustrated embodiment, the first and second support portions31 and 32 are shown as beads recessed inward of the tubular portion 26.

Moreover, in correlation of the clamping portions 35 b and 35 c of thefastening portion 35, the first support portion 31 and the secondsupport portion 32, the clamping portions 35 b and 35 c of the fasteningportion 35 and the second support portion 32 are located in asubstantially opposite area from the first support portion 31 in thecircumference of the greater diameter portion 22 of the inflator body 21based on the center C of a cross section of the body 21 as mounted onthe seat back 2. In other words, when the inflator 20 is mounted on theseat back 2, or when the inflator 20 is arranged substantiallyvertically to locate the small diameter portion 23 at upper end, theclamping portions 35 b and 35 c and the second support portion 32 arelocated in an area directed toward vehicle's front, and the firstsupport portion 31 is located in an area directed toward vehicle's rear.

To mount the airbag device M on the vehicle, as shown in FIGS. 7A and7B, the retainer 25 of the inflator 20 with a side of the cover portion28 at the head is put in the airbag 15 from the insert hole 15 cfirstly, such that the bolts 37 are projected out of the airbag 15 fromthrough holes 16. At this time, the fastening portion 35 of the retainer25 is left exposed outside of the airbag 15.

Then as shown in FIGS. 7B and 7C, the airbag 15 is folded. After foldingthe airbag 15, a breakable wrapping sheet 11 as shown in FIG. 2 iswrapped around the airbag 15 for keeping folded-up configuration. Infolding the airbag 15, the fastening portion 35 of the retainer 25 iskept exposed. The fastening portion 35 is kept exposed when the airbag15 is wrapped by the wrapping sheet 11.

Then as shown in FIGS. 7C and 7D, the inflator body 21 with the smalldiameter portion 23 at the head is inserted into the retainer 25 fromthe opening 26 b of the retainer 25 until an end face of the greaterdiameter portion 22 abuts against the positioning projection 26 c. Asshown in FIGS. 9A and 9B, subsequently, the knob portion 35 a of thefastening portion 35 of the retainer 25 are held and plasticallydeformed, so that the clamping portions 35 b and 35 c of the fasteningportion 35 and the first and second support portions 31 and 32 arepressed onto the circumference of the greater diameter portion 22 of theinflator body 21. Thus the body 21 is held by the retainer 25 and anassembling work of the airbag device M is completed. The harness 39 ispreliminarily connected to the body 21.

The airbag device M thus assembled is mounted on the seat back 2 of theseat 1 by fastening the bolts 37 into nuts 7 on the seat frame 3. Afterthe mounting of the airbag device M, the seat 1 is covered by thesurface skins 5 and 6 to finish, and is mounted on the vehicle. Inmounting the seat 1 on the vehicle, the harness 39 leading from theinflator body 21 is connected to a predetermined airbag actuatingcircuit of the vehicle.

When predetermined signals are inputted to the inflator body 21 throughthe harness 39 after the side impact airbag device M is mounted on thevehicle, inflation gas is discharged from the gas discharge ports 23 aof the inflator body 21. Then the airbag 15 breaks the wrapping sheet11, pushes the edge portion 4 a of the cushion 4 to open separated fromthe center portion 4 b, and deploys as indicated by double-dotted linesin FIGS. 1 and 2.

In the inflator 20 of the side impact airbag device M according to thepresent invention, the fastening portion 35 is located at an end of theretainer 25. This enables the fastening portion 35 of the retainer 25 tobe exposed out of the airbag 15 when inserting the retainer 25 into theairbag 15 from the insert hole 15 c, and further enables the airbag 15to be folded up in that state. Moreover, since the fastening portion 35is exposed out of the airbag 15 after the airbag 15 is folded up, theinflator body 21 can be inserted into the retainer 25 from the opening26 b, and the knob portion 35 a of the fastening portion 35 exposed outof the airbag 15 can be fastened directly, not from outside of theairbag 15. Accordingly, the inflator body 21 is easily joined with theretainer 25 having been put in the folded airbag 15 without damaging theairbag 15. In addition, the body 21 is easily set in the retainer 25merely by inserting the body 21 into the retainer 25.

Moreover, the retainer 25 includes the clamping portions 35 b and 35 cof the fastening portion 35 and the first and second support portions 31and 32 all of which are arranged along the axial direction of theinflator body 21 to abut against the circumference of the greaterdiameter portion 22. In the circumference of the greater diameterportion 22 of the inflator body 21 based on the center C of a crosssection of the body 21 as mounted on the seat back 2, the clampingportions 35 b and 35 c of the fastening portion 35 and the secondsupport portion 32 are located in a substantially opposite area from thefirst support portion 31. Accordingly, when the knob portion 35 a of thefastening portion 35 is plastically deformed and recessed inward toassemble the inflator body 21 with the retainer 25, the inflator body 21functions as a lever. As shown in FIG. 5, more specifically, theclamping portions 35 b and 35 c of the fastening portion 35 serves aseffort-point, the first support portion 31 serves as a fulcrum, and thesecond support portion 32 as an application-point, such that the secondsupport portion 32 is pressed onto the body 21. In other words, theinflator body 21 is stably supported at least at three positions in theaxial direction by the clamping portions 35 b and 35 c of the fasteningportion 35, and the first and second support portions 31 and 32.

Of course, although the retainer 25 includes the bolts 37 as mountingmeans projected outward radially, the retainer 25 is located inside theairbag 15 smoothly since it is inserted into the airbag 15 before beingfolded up.

Therefore, in the inflator 20 in the foregoing embodiment, the inflatorbody 21 is easily joined with the retainer 25 even if the retainer 25has already been put in the folded airbag 15. Moreover, the folding workof the airbag 15 is facilitated since the airbag 15 is folded up in astate only the retainer 25 is inside the airbag 15 before the inflatorbody 21, which generates inflation gas, is inserted into the airbag 15.

As an inflator 20, it is sufficient that the fastening portion 35 of theretainer 25 is exposed outside of the airbag upon fastening thefastening portion 35. Accordingly, for example, it will also beappreciated that an airbag is folded in a state an entire retainer 25except bolts 37 as mounting means is disposed inside the airbag, theinflator body 21 is inserted into the retainer 25 from a predeterminedinsert hole of the airbag, and that the fastening portion 35 located atan end portion of the inflator 20 disposed proximate to the insert holeis exposed by turning back an edge of the insert hole of the airbag, andthen fastening work is applied. Thereafter, the edge of the insert holeof the airbag is restored.

However, if the inflator 20 is configured so that the fastening portion35 of the retainer 25 is projected from the airbag 15 in the foldingstep of the airbag 15, as in the foregoing embodiment, the assemblingwork of the airbag device M is even more facilitated since there is noneed to turn over and restore the edge of the insert hole 15 c of theairbag 15.

Moreover, in the body 21 of the inflator 20 of the foregoing embodiment,the gas discharge ports 23 a are located at an end side, i.e., at upperend side apart from the fastening portion 35 so that inflation gas issupplied into the airbag 15 from the openings 26 a and 27 located in theupper end vicinity apart from the fastening portion 35. Accordingly,after the inflator body 21 is inserted into the retainer 25 having beenalready disposed in the airbag 15 from the insert hole 15 c of theairbag 15, even if the insert hole 15 c is not closed by stitching orthe like, inflation gas does not unexpectedly flows out in the course ofinflation. In the foregoing embodiment, the insert hole 15 c locatedapart from the gas discharge ports 23 a serves as a vent hole fordischarging extra gas after completion of inflation of the airbag 15,and therefore, should not be closed.

With respect to arrangement position of the gas discharge ports 23 a, toprevent gas leakage from the insert hole 15 c in the course of airbaginflation, the discharge ports 23 a are desirably in positions apartfrom the fastening portion 35 than a middle point of an entire length ofthe inflator body 21, i.e., in upper end or leading end vicinity, tospeak on the basis of the body 21 of the inflator 20. To speak on thebasis of the retainer 25, the discharge ports 23 a are desirably inpositions apart from the fastening portion 35 than the first supportportion 31, i.e., in upper end or leading end vicinity. More desirably,the discharge ports 23 a are located apart from the fastening portion 35than the second support portion 32, i.e., in upper end or leading endvicinity.

The retainer 25 of the inflator 20 includes a positioning projection 26c that abuts against an end face of the leading end of the inflator body21 i.e., an end face of the greater diameter portion 22 located awayfrom the fastening portion 35, when inserted from a side of thefastening portion 35 before fastened, for positioning the body 21 in theretainer 25. Therefore, the inflator body 21 is easily positioned in theretainer 25 which is disposed invisibly in the airbag 15 merely byapplying the leading end face to the positioning projection 26 c, whichfacilitates the assembling work of the airbag device M.

Moreover, in the inflator 20, the second support portion 32 of theretainer 25 is located in the vicinity of the other end portion of theretainer 25 opposite from the fastening portion 35. With thisconstruction, the inflator body 21 is held in the longest span betweenthe clamping portions 35 b and 35 c of the fastening portion 35 and thesecond support portion 32 each of which is located in the vicinity ofend of the retainer 25. Therefore, the retainer 25 holds the body 21stably.

In the meantime, the first support portion 31 of the retainer 25 islocated substantially in the axially middle of the retainer 25. That is,the first support portion 31 is in the vicinity of the middle positionbetween the clamping portions 35 b and 35 c of the fastening portion 35and the second support portion 32. Therefore, the retainer 25 holds theretainer 25 well-balancedly.

In addition, the first support portion 31 and the second support portion32 of the retainer 25 are beads that are made by pressing a sheet metalforming the retainer 25 such that projections are provided. With thisconstruction, the first and second support portions 31 and 32 are easilymade by pressing work.

In the inflator 20, the retainer 25 axially holds the inflator body 21utilizing the fastening portion 35 and the first and second supportportions 31 and 32, and the fastening portion 35 has two contact pointsthat contact the circumference of the inflator body 21 as the clampingportions 35 b and 35 c, while each of the first and second supportportions 31 and 32 has one contact point. However, it is sufficient thatthe clamping portions of the fastening portion 35 and the second supportportion 32 are located in substantially opposite area from the firstsupport portion 31 in the circumference of the greater diameter portion22 of the body 21 based on the center C of a cross section of the body21 taken perpendicularly to the axial direction of the body 21, andtherefore, contact point of the fastening portion 35 and the first andsecond support portions 31 and 32 to the circumference of the body 21may be one, or in plurality, including a case that a contact portion iselongate in the circumferential direction of the body 21.

However, if the clamping portions 35 b and 35 c are provided in twopositions in the circumferential direction of the retainer 25 as in thefastening portion 35 of the foregoing embodiment, the clamping portions35 b and 35 c hold the body 21 at two points, so that the body 21 isprevented from being dislocated in a direction perpendicular to theaxial direction, and the retainer 25 holds the body 21 stably. At thistime, a circumferential middle point between the clamping portions 35 band 35 c is located in substantially opposite point from the firstsupport portion 31 in the circumference of the body 21 based on thecenter C of a cross section of the body 21 taken perpendicularly to theaxial direction of the body 21.

The construction of having two clamping portions may also be applied tothe first and second support portions not only to the fastening portion35. In a retainer 25A of an inflator 20A shown in FIGS. 10 to 12, forexample, a first support portion 31A and a second support portion 32Aboth include two clamping portions 31 a, 31 b, 32 a and 32 b,respectively, which project inward to abut against the circumference ofthe inflator body 21 when fastened. A circumferential middle pointbetween the clamping portions 31 a and 31 b is located in asubstantially opposite point from a circumferential middle point betweenthe clamping portions 35 b and 35 c in the circumference of the body 21based on the center C of a cross section of the body 21 takenperpendicularly to the axial direction of the body 21. A circumferentialmiddle point between the clamping portions 32 a and 32 b issubstantially consistent with the circumferential middle point betweenthe clamping portions 35 b and 35 c in the circumference of the body 21based on the center C of a cross section of the body 21 takenperpendicularly to the axial direction of the body 21.

As retainers 25B and 25C of inflators 20B and 20C shown in FIGS. 14 to21, it will also be appreciated that the second support portion 32B/32Cincludes two clamping portions 32 a and 32 b while the first supportportion 31B/31C includes one clamping portion. The first support portion31B shown in FIGS. 14 to 17 is formed into a bead extending flatly inaxial direction of the retainer 25B by pressing work, and the firstsupport portion 31C shown in FIGS. 18 to 21 is formed into a bead curvedand projected inward of the retainer 25C by pressing work.

Moreover, as an inflator 20D shown in FIG. 22, it will also beappreciated that a first support portion 31D includes two clampingportions 31 a and 31 b while the second support portion 32D includes oneclamping portion.

In each of the retainers 25A, 25B, 25C and 25D, the first supportportion 31A, 31B, 31C or 31D is located in substantially axial middlepoint between the fastening portion 35 and the second support portion32A, 32B, 32C or 31D.

Although the foregoing embodiments are described as applied to the sideimpact airbag device M mounted on a seat, it is not intended to belimited thereby. The present invention may also be applied to inflatorsemployed in various airbag devices such as a knee-protecting airbagdevice and an airbag device for pedestrian-protection, on condition thatthe airbag devices include an inflator which includes a substantiallycylindrical body for generating inflation gas and a substantiallytubular retainer made of sheet metal for holding the body from outside,and that the retainer includes a mounting means such as bolts formounting the airbag to amounting position, and holds the inserted bodyby fastening a fastening portion thereof.

The mounting means provided in the retainer 25 should not be limited tobolts 37 described in the foregoing embodiments, but also may be nuts, amounting bracket with a nut, or a mounting pin.

The clamping portions 35 b and 35 c of the fastening portion 35 and thesecond support portion 32 in the retainer 25 are located in a positionat substantially 180° from the first support potion 31 in thecircumference of the body 21 based on the center C of the cross sectionof the body 21. However, it is sufficient that the clamping portions 35b and 35 c of the fastening portion 35 and the second support portion 32are located in a position away at least 90° from the first supportpotion 31 in the circumference of the body 21 based on the center C ofthe cross section of the body 21, as long as the retainer 25 holds thebody 21 functioning like a lever by utilizing the first support portion31 as fulcrum, and the fastening portion 35 and the second supportportion 32 as effort-point and application-point.

1. An inflator for supplying inflation gas to an airbag of airbag devicefor automobile which is used in an inserted state in the airbag, theinflator comprising: a substantially cylindrical body for generatinginflation gas; and a substantially tubular retainer made of sheet metalfor being mounted around the body, the retainer including a mountingmember for mounting the airbag to a predetermined mounting position andan element for holding the body, the element for holding the bodyconsisting of: a fastening portion located in a vicinity of one end ofthe retainer for fastening on the body to deform plastically andprotrude inward after the body of the inflator is inserted into theretainer which has been set inside the airbag in advance of the body; afirst support portion projecting inward from an inner circumference ofthe retainer; and a second support portion projecting inward from theinner circumference of the retainer, wherein the fastening portion, thefirst support portion and the second support portion are arranged inorder along axial direction of the body to abut against a circumferenceof the body, whereby the retainer holds the body at least at three axialpositions by the fastening portion, the first support portion and thesecond support portion, and the fastening portion and the second supportportion are located in a top portion on an outer circumference of thebody and the first support portion is located in a bottom portion on anouter circumference of the body based on a center of a cross section ofthe body taken perpendicularly to the axial direction of the body as theretainer holds the body, wherein the top portion is substantiallyopposite to the bottom portion.
 2. The inflator according to claim 1,wherein the fastening portion is projected from the airbag when theinflator is inserted and located in the airbag.
 3. The inflatoraccording to claim 1, wherein gas discharge ports of the body arelocated at an end of the body apart from the fastening portion, suchthat inflation gas is fed to the airbag from a location apart from thefastening portion.
 4. The inflator according to claim 1, wherein theretainer comprises a positioning projection for positioning the body inthe retainer by abutting against the body when the body is inserted intothe retainer from a side of the fastening portion before fastened. 5.The inflator according to claim 1, wherein the second support portion islocated in the vicinity of an end of the retainer apart from the otherend having the fastening portion.
 6. The inflator according to claim 1,wherein the first support portion is located substantially in an axialmiddle position in the retainer.
 7. The inflator according to claim 1,wherein the first support portion and the second support portion arebeads that are made by pressing a sheet metal forming the retainer. 8.The inflator according to claim 1, wherein at least one of the fasteningportion, the first support portion, or the second support portionincludes two contact points that project inward and contact thecircumference of the body, the contact points are arranged along acircumferential direction of the retainer.
 9. The inflator according toclaim 1, wherein when fastening the fastening portion to the body, thefastening portion, the first support portion and the second supportportion are pressed against the body by a leverage where the fasteningportion is an effort-point, the first support portion is a fulcrum, andthe second support portion is an application point, such that the bodyis held by the retainer.
 10. An inflator for supplying inflation gas toan airbag of airbag device for automobile which is used in an insertedstate in the airbag, the inflator comprising: a substantiallycylindrical body for generating inflation gas; and a substantiallytubular retainer made of sheet metal for being mounted around the body,the retainer including a mounting member for mounting the airbag to apredetermined mounting position and a tubular portion for holding thebody, the tubular portion consisting of: a fastening portion located ina vicinity of one end of the retainer for fastening on the body todeform plastically and protrude inward after the body of the inflator isinserted into the retainer which has been set inside the airbag inadvance of the body; a first support portion projecting inward from aninner circumference of the retainer; and a second support portionprojecting inward from the inner circumference of the retainer, whereinthe fastening portion, the first support portion and the second supportportion are arranged in order along axial direction of the body to abutagainst a circumference of the body, whereby the retainer holds the bodyat least at three axial positions by the fastening portion, the firstsupport portion and the second support portion, and the fasteningportion and the second support portion are located only in a top portionon an outer circumference of the body and the first support portion islocated only in a bottom portion on an outer circumference of the bodybased on a center of a cross section of the body taken perpendicularlyto the axial direction of the body as the retainer holds the body,wherein the top portion is substantially opposite to the bottom portion.11. An inflator for supplying inflation gas to an airbag of airbagdevice for automobile which is used in an inserted state in the airbag,the inflator comprising: a substantially cylindrical body for generatinginflation gas; and a substantially tubular retainer made of sheet metalfor being mounted around the body, the retainer consisting of a mountingmember for mounting the airbag to a predetermined mounting position, afastening portion, a first support portion and a second support portion,wherein: the first support portion and the second support portion arepreliminarily formed on an inner circumference of the retainer beforethe retainer is mounted around the body; the fastening portion isfastened on the body to deform plastically and protrude inward after theretainer is mounted around the body; while the fastening portion islocated in the vicinity of one end of the retainer, the fasteningportion, the first support portion and the second support portion arearranged in order along axial direction of the body to abut against acircumference of the body, whereby the retainer holds the body at leastat three axial positions by the fastening portion, the first supportportion and the second support portion; and the fastening portion andthe second support portion are located in a top portion on an outercircumference of the body and the first support portion is located in abottom portion on an outer circumference of the body based on a centerof a cross section of the body taken perpendicularly to the axialdirection of the body as the retainer holds the body, wherein the topportion is substantially opposite to the bottom portion.